Unable to send emails to a specific domain

Unable to send emails to a specific domain

I'm not able to send emails to my accounting office with my e-mail hosted here, from my personal e-mail it's OK. Every e-mail I send, I receive this:

This message was created automatically by mail delivery software. 
A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. 

alex@deltabc.com.br INVALID_ADDRESS, ERROR_CODE :550, ERROR_CODE :5.7.1 <alex@deltabc.com.br>: Recipient address rejected: Message rejected due to: SPF fail - not authorized. Please see http://www.openspf.net/Why?s=mfrom;id=bruno@c2biz.net;ip=74.201.84.163;r=alex@deltabc.com.br 



Received:from [192.168.25.237] (191.248.160.20 [191.248.160.20]) by mx.zohomail.com 
    with SMTPS id 1474373813889874.1793611678463; Tue, 20 Sep 2016 05:16:53 -0700 (PDT) 
Message-ID:<80A91938-6369-4C2B-9370-C9559352FE7F@c2biz.net> 
Date:Tue, 20 Sep 2016 09:16:52 -0300 
From:Bruno Dalmazo <bruno@c2biz.net> 
To:Alex Rodrigues <alex@deltabc.com.br> 
Subject:Mensalidades em aberto 
Content-Type:text/plain; charset=utf-8

Or

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. 


kelly@deltabc.com.br INVALID_ADDRESS, ERROR_CODE :550, ERROR_CODE :5.7.1 <kelly@deltabc.com.br>: Recipient address rejected: Message rejected due to: SPF fail - not authorized. Please see http://www.openspf.net/Why?s=mfrom;id=bruno@c2biz.net;ip=74.201.84.163;r=kelly@deltabc.com.br


alex@deltabc.com.br INVALID_ADDRESS, ERROR_CODE :550, ERROR_CODE :5.7.1 <alex@deltabc.com.br>: Recipient address rejected: Received-SPF: Fail (SPF fail - not authorized) identity=mailfrom; client-ip=74.201.84.163; helo=sender163-mail.zoho.com; envelope-from=bruno@c2biz.net; receiver=kelly@deltabc.com.br 




Received:from [192.168.25.237] (191.248.160.20 [191.248.160.20]) by mx.zohomail.com

with SMTPS id 1474373790711869.3384187691826; Tue, 20 Sep 2016 05:16:30 -0700 (PDT)

Message-ID:<47B9074B-8455-4F88-B65A-3087B4218F16@c2biz.net>

Date:Tue, 20 Sep 2016 09:16:24 -0300

From:Bruno Dalmazo <bruno@c2biz.net>

To:Kelly Freitas <kelly@deltabc.com.br>

Cc:Alex Rodrigues <alex@deltabc.com.br>

Subject:Re: DELTA BERRINI - TERMO ADITIVO MUDANÇA DE PLANO

Content-Type:multipart/alternative; boundary="Apple-Mail=_199487DC-34F4-4CF3-82AC-088CEF103118"